Matthew Garnett, 15, was sectioned under the Mental Health Act to a psychiatric intensive care unit - usually for short-term emergency admissions - in September last year after attacking members of his family.

It was reported on the weekend that Matthew would be moved to a specialist facility after more than 150,000 people backed a petition by his parents to end his six-month "jail sentence" in the psychiatric ward.

"The widespread media coverage has actually damaged the petition, as people think the issue has been resolved, when it hasn't," Mr Garnett told The Huffington Post UK.

"For anyone on the outside it looks like things have gotten better, but if you delve a littler further it's the same story as it's been since September.

"He thinks he's in prison and he is being punished for attacking us".

Although Matthew was referred to St Andrew's Healthcare in Northampton last September, Mr Garnett says his son is still residing in a ward in Woking, Surrey.

"The issue is that there isn't a bed available. In September we were told it would be a few weeks. Then they said October, then November, Christmas, January.

"That statement [the NHS gave to media] has been the same for months."

Mr Garnett accused the NHS of being "faceless", adding that requests for a specific point of contact were rejected.

"Since last week our local authority has been investigating on our behalf and talking to the NHS. But it's always second-hand information," he said.

The lack of beds is part of a wider issue; the Garnett family were offered Northampton, and the only other units are in Newcastle and Birmingham.

Matthew's parents petitioned Alistair Burt, minister for community and social care, and NHS England chief executive Simon Stevens and launched a social media campaign using the hashtag makeroomformatthew.

The family hope he will one day be able to return home and receive treatment in the community but Mr Garnett said he feared it was "just the start" and there were hundreds more families going through similar experiences.

The Royal College of Psychiatrists criticised the system last year, saying it needed to be improved, as more than 2,000 psychiatric beds have been closed across England since 2011.

"There is not a single bed available in the southern part of the country. We don't know how it will work, but we will just have to accept it. It's going to make transitioning Matthew back into school and home a lot harder, as he'll be so far away," Mr Garnett said.

The NHS has been contacted for an updated statement.

Previously, a spokesperson for NHS England said: "We have every sympathy for Matthew and his family and we understand that this has been a very difficult time.

"It has been confirmed that Matthew will be moved to St Andrew's, where he will be able to receive the specialist care that he needs. We anticipate that this will happen in a matter of weeks but cannot confirm an admission date at this point."

Matthew was sectioned, with the family's agreement, after his violent outbursts "escalated in severity" until, on September 4, police were called following an attack on his father.

Mr Garnett said: "He's never been able to control his emotions - he's kind of like a toddler.

"The police were amazing. We called them three or four times and they have always been uniformly brilliant, recognising it's a mental health issue not a criminal thing.

"We were desperate he did not get taken into some hideous criminal process but it was clearly not safe for him to be in the house with his family - we were not offered any other route to go."

Charity bosses have also weighed in, claiming Matthew's case was an "an opportunity to restore faith, where so far there has been repeated failure, and build the support for people with a learning disability and the support families want and need and have been promised," Jan Tregelles, Chief Executive at Mencap, and Viv Cooper, Chief Executive at the Challenging Behaviour Foundation, said.

"People with a learning disability and their families have endured five years of failure by national and local government and the NHS to bring about meaningful change for the 3,500 people confined to inpatient units in England.

"Despite promises to move people out of inpatient units and ensure they get the right support in their local communities many people are still stuck in these units, where they are at increased risk of abuse and neglect and often unacceptably far from loved ones. Perhaps most shocking is the fact that 165 of these people are children under the age of 18," Tregelles and Cooper added.